1. Field of the Invention
This invention relates to a plant bed such as grassland or sod having means for protecting the roots of the plants from the feeding damage by the larval stage of certain insects, such as the European Chafer and the Japanese Beetle. More specifically, this invention relates to a grass product and method for manufacturing the same, which is substantially protected or free from feeding damage by the larval stage of certain insects.
2. Description of the Prior Art
It is known in the art, of which U.S. Pat. No. 2,605,589 is exemplary, to provide a grass bearing lamina to be used as a covering for lawns, terraces and the like. To facilitate transportation of units of the lamina, grass seed is planted in rooting material above a plastic mesh, and the materials of the lamina are held together by the grass roots of the germinated seed which become embedded in the plastic mesh.
U.S. Pat. No. 1,971,504 discloses a seed product comprising a layer of water-soluble fertilizer, and upper layer containing seeds and a flexible plastic material interposed between the fertilizer and seeds to keep the acidity of the fertilizer from adversely affecting the seeds. U.S. Pat. No. 3,812,618 discloses a seed-foam-fabric composite in which the seeds are disposed in particle portions of foam which are attached to the upper surface of a fabric backing.
U.S. Pat. No. 3,863,388 discloses a multi-layer grass unit in which an impervious barrier is positioned at the bottom of the unit, a mesh unit is located on or slightly above the impervious barrier, grass seed is placed on or slightly above the impervious barrier, and rooting material placed over the mesh and seed. Upon germination of the seeds, the grass roots cannot pass through the impervious layer and hence move laterally and then upwardly through the mesh openings to bind the seeds, screen and rooting material together in such a fashion that they can be separated as a unit from the impervious layer or barrier. The grass unit can then be transferred to a lawn or the like where the grass will then continue to grow with the roots now moving downwardly through the mesh and into the soil.
A disadvantage common to all of the aforementioned grass products is that the roots of the germinated grass seeds are mostly above the screen or mesh and hence the screen would not be effective in preventing insects such as grubs in the upper layer from attacking the grass roots and killing the grass.